During marine operations, electronic naval chart plotters are usually used for displaying a naval chart on a screen, in true or relative course projection. The vessel usually also has a position calculating unit such as a global positioning system (GPS) sending signals to the chart plotter so as for enabling the chart plotter unit to compute an appropriate section of the chart in a desired scale. It is further common usage to display the vessel itself generally centrally in the consecutively projected chart section as a boat-shaped symbol with the vessel's course track and heading indicated. Most civilian vessels above a given tonnage are furnished with an automatic identification system (AIS) broadcasting the vessel's position and identification signal. Such broadcasted AIS-information when received by an AIS-receiver may also be forwarded to a chart plotter and display such civilian vessels as symbols in their relevant positions on the chart plotter.
The applicants have previously disclosed a stabilized searchlight which is connected to acceleration sensors and arranged for keeping the light cone fixed on an object in an arbitrarily selected position at the sea surface. During the stabilizing process the object's position is calculated and registered. This may be useful from a safety-at-sea point of view so as for ensuring that a found object is not lost out of sight and, if possibly, reported to other vessels that may take over handling the object whether it has a correspondingly working searchlight or not.
However, it is desirable to have more than one local searchlight on one single vessel. A searchlight may provide much information as such but there is a strong need for collecting such information in a way that enables acquisition and mutual distribution to several participating parts in a marine search operation, such as in routinely conducted operations as search for instrument buoys, mooring devices, flotsam or oil slicks, but also for more critical search and rescue operations for finding a vessel, a life raft or lifeboat, and not the least a search for one or more men overboard. In such situations it is highly desirable that all available vessels being capable of constructively contributing to the rescue operation arrive at the search area as soon as possible and that they are efficiently directed. It is common practice to conduct visual observation and radar search, but it is not widespread practice to share information in other ways than by oral or other radio communication. The applicants are at the time of filing not aware of systems that may meet the demand for coordinating the information exchange during search operations and for distributing the information in a way that may contribute to facilitate the coordination of localizing objects in the sea, or for finding a missing object in the sea in a coordinated and expedite way.